The invention relates to a device for displacing the cylinder block and cylinder head versus the crankcase.
It is known to rate the compression ratio of Otto engines based on an anti-knocking property under full-load operating conditions. Under partial-load operating conditions of the internal combustion engine, the efficiency losses are accepted because higher compression ratios could be theoretically obtained in that range. To raise the compression ratio under partial-load operating conditions, the combustion chambers can be designed in a variable or shifting manner. The spacing between the piston and the cylinder head, and thus the volume of the combustion chamber and thereby also the compression ratio are changed by swiveling or displacing the entire cylinder head.
A device for displacing the cylinder block and cylinder head versus the crankcase to change the compression, on the engine block that has the type of construction described in the follow-wing, is known from European Patent Application EP 0 426 540 A1.
A crankcase that receives the crankshaft comprises setting (or adjusting) shafts with eccentrics that are supported on both sides of the crankshaft. These setting shafts are distributed over the length of the crankcases in an alternating manner and engage receiving bores of bearing bridges or bearing arms of the cylinder block that are arranged on both sides of the axis of the crankshaft. The cylinder block with the cylinder head forms a coupling member between the eccentrics and is displaced in relation to the crankshaft when the eccentrics are rotated. The straight line of connection between the axes of the setting shafts extends around the area of the crankshaft above or below the crankshaft and intersects the axis of the cylinder at a slanted or, according to FIG. 18, of EP 0426540 A1 at a right angle.
In addition, to duplicate the cylinder block and cylinder head versus the crankcase, the cylinder block can be pivot mounted on the one side at the level of the end of the cylinders sleeves in the crankcase. In addition, the cylinder block can be swivelled on the other side of the axis of the crankshaft via a crank drive supported on the crankcase. The cylinder block assumes positions that are closer to, or farther removed from the crankshaft to varying degrees, to change the compression in the engine (Auto-Zeitung 10/2000, pages 68-69, Heinrich Bauer Zeitschriften Verlag KG, Hamburg). A drawback of this design is the unfavorable introduction of force from the cylinder block into the crankcase and for typing up the transmission. The setting mechanism, which is formed as a crank drive consists of an eccentric shaft with connecting rods, and requires substantial installation space and a larger number of components. This design requires greater flexibility of the intake gas and exhaust gas system for compensating movements because of the pivoting movement of the cylinder block and cylinder head.